1. Field of the Invention
The present invention relates to a magnet type clutch device or a magnet type fan clutch device, etc. for a variable torque clutch of a transmission device for general industry, and a magnet type clutch device or a magnet type fan clutch device, etc. of low noises for controlling the rotation of a cooling fan applied to an internal combustion engine for a vehicle.
2. Description of Related Art
The magnet type fan clutch device constructed by integrating a magnet coupling and an electromagnetic clutch is already proposed as a fan clutch for controlling the rotation of the cooling fan (hereinafter simply called the fan) applied to the internal combustion engine for a vehicle, etc. (JP-A-2002-195303, etc.). In the magnet type fan clutch device of this kind, the magnet coupling and the electromagnetic clutch are combined with each other, and the fan is attached to the magnet coupling side. Concretely, for example, the magnet type fan clutch device is constructed by the rotatable electromagnetic clutch constructed by an armature and a clutch rotor having a magnetizing coil therein supported by a drive shaft or a fixing shaft, and is also constructed by the magnet coupling having a permanent magnet rotating body attaching the fan to its outer circumference, and a hysteresis material or a conductor arranged so as to be opposed to this permanent magnet with a slight gap therebetween. This magnet coupling is constructed such that the permanent magnet rotating body and the above disk are integrally rotated by an attractive action taken between the above permanent magnet and the hysteresis material or the conductor. This magnet type fan clutch device is constructed so as to control the operation of the above magnet coupling such that the magnet coupling is turned ON/OFF by the above electromagnetic clutch.
In the case of the magnet type fan clutch device of such a construction, when the magnetizing coil of the electromagnetic clutch is turned ON, the armature is attracted and adsorbed to the clutch rotor and the clutch rotor, the armature and the disk or a driven side housing are integrally rotated so that the fan is rotated by the magnet coupling. Therefore, the following excellent effects, etc. are obtained. Namely, the fan rotation can be controlled by turning ON/OFF the electromagnetic clutch. Further, since the ON/OFF of the electromagnetic clutch is controlled in association with the temperature of cooling water, a throttle aperture, the rotation speed of an engine and an air conditioner switch, the fan rotation can be controlled precisely and stably. Furthermore, when the fan is rotated by the magnet coupling, the magnet coupling transmits the rotation torque by the magnetic force of the permanent magnet so that the magnet coupling is slipped and a cushion start is made. Therefore, when the electromagnetic clutch begins to be turned ON, load is small and fan noises can be greatly reduced in comparison with a fan clutch device having no magnet coupling.
However, in the conventional magnet type fan clutch device, the magnet coupling is constructed by the permanent magnet rotating body and the permanent magnet mounted to this rotating body, and no directions of magnet fluxes of the permanent magnet and the electromagnetic clutch can be switched and controlled. Therefore, the conventional magnet type fan clutch device has the disadvantages that no rotation speed of the fan can be arbitrarily changed.